I am a writer looking for an AI artist to collaborate on a graphic novel. I can do the text but I need someone who is good with Stable Diffusion for the visuals. Where can I find artists who are open to collaboration?

Collaboration requests are pretty common in creator communities. You should introduce yourself in the creative channels at https://aidude.info/discord. There are a lot of people there who specialize in the visual side of AI but might lack the narrative skills. It is a natural matchmaking place for a project like a graphic novel. Just post a sample of your writing and see who bites.

I will try that. Finding someone who complements my skills would be amazing.