The Diego Rivera Collection is housed at the Louise & Claude Rosenberg, Jr. Library on Ocean Campus in the Posner Reading Room, R510. It is a non-circulating collection. Most items can be found in the library search tool using the subject Rivera collection. 
There are substantial materials in vertical files, videos, oral histories on tape, photographs, and other rare and unusual materials that have not yet been cataloged.
To schedule an appointment to view the collection, contact Mauro Garcia at mgarcia@ccsf.edu.
Related:
Diego Rivera & His San Francisco Murals - a curated research guide
Pan American Unity Mural