I admit, it's not a graphic novel, but there are plenty based on King's works. Insomnia is a fantastic novel, but nobody has attempted a film adaptation....yet. It's in development hell in Hollywood, and it's disappointing, but I understand why. A movie of Insomnia would have high production values, and a proper adaptation would have some trippy elements to it.
Summary from eNotes.
Stephen King has established himself as one of the most popular authors of the last twenty years. He has taken the horror genre and molded it to serve his own purposes. In addition to being a master at scaring his reading public, King has the remarkable ability of presenting popular American culture with all of its crassness and sentimentality. Some of his most successful works include CARRIE (1974), THE SHINING (1977), IT (1986), NEEDFUL THINGS (1991), and GERALD’S GAME (1992). INSOMNIA is set in the town of Derry, Maine. King used Derry as the setting for his thrilling novel IT. A recent widower, seventy-year-old Ralph Roberts finds himself waking up earlier and earlier each day. Struggling to recover from the death of his wife, Roberts is at a loss to find a cure for his insomnia. He is also a witness to the bizarre behavior of someone he knows. Ed Deepneau, a chemist, is involved in a car accident where his car crashes into a fertilizer truck, but then Deepneau makes wild accusations toward the driver involving the transport of dead fetuses. Deepneau’s wife, Helen, is also discovered to have been beaten by him. Unable to understand his own insomnia, Roberts is equally baffled over what has happened to Deepneau.
In addition to losing sleep, Roberts is startled to discover that he can see auras of various colors surrounding people who he comes across in town. He does not know what to make of this phenomena. Roberts discovers, however, that his neighbor Lois Chasse is experiencing the same symptoms. She is also widowed and the two of them find comfort in each other’s company. Eventually, they become romantically linked, but first they must unravel the mystery of the auras and various other troubling happenings in Derry. The town is being torn apart by the issue of abortion and the prospect of a nationally known abortion rights leader coming to Derry to deliver a speech. With this as a backdrop, King sets in motion a terrifying tale of good versus evil, and of life versus death. Roberts seemingly has been chosen to intercede against the forces of chaos. INSOMNIA is a roller-coaster ride through a world that is coming apart at the seams. The ending may be somewhat of a disappointment and the novel is longer than necessary, but INSOMNIA still remains one of King’s most imaginative works and a must read for the millions of King fans.
Patrick Stewart as Ralph Roberts
Patrick Stewart looks exactly how I envisioned Ralph to look like. Also, Stewart is a fantastic actor who could carry the movie if need be.
Annette O'Toole as Lois Chasse
Annette looks younger than she is, but with some makeup she could properly play the role. Actors hardly play their own age anyway.
Edward Norton as Ed Deepneau
Once again, Norton's acting and looks are exactly what I imagined Ed would look like when I read the novel.
Michael Clarke Duncan as the voice of The Crimson King
The Crimson King is a villain at the end of the story, and he also takes part in many other Stephen King novels including: The Dark Tower. I imagine he would have a dark, and ominous voice. I'm willing to trade Duncan for somebody else though, perhaps James Earl Jones :)

If you've ever seen the Disney movie, Hercules, you know what The Fates are. The Fates are main characters in Insomnia, and they are meant to hint that Greek Mythology may have quite a bit to do with King's Multiverse of stories. All of Stephen King's books take place in a universe he has created, where stories and characters intertwine or meet up together. The Crimson King is a main villain of his story. If you ever read the book, It, or seen the movie, It the clown is an evil spirit who might be an agent of the Crimson King. It, or Pennywise the Clown, appears as a mist that King calls, "The Deadlights" in the novel. If you remember from Greek mythos, humans see mythical beasts as mist because they are unable to comprehend the true form of the creature. Hence, the reason why It must appear as something that children would be attracted to.
Anyway, The Fates are in Insomnia. They appear as little bald doctors to Ralph though. I'm unsure who to cast as them. Perhaps someone like Andy Serkis could play all three?