The libraries have a large and growing collection of graphic novels, and you can find them in GIL-Find, the library catalog. You can search by the title or the author of a specific graphic novel just like any other book.
If you'd like to browse the collection, search for "graphic novel" in GIL-Find, then select a specific campus's collection under "Location" on the left side of your search results. Some Perimeter campuses have separate sections just for graphic novels. At Atlanta campus, they're with the regular books shelved by call number.
You can request any graphic novel to be send to the campus that's most convenient for you for free.