Remember, "diversity" is a broad subject - you can make a more targeted search by focusing on more specific topics and choosing more specific keywords, like "workplace discrimination" or "media representation." Also keep in mind that many diverse groups have multiple naming conventions, so you might want to try looking up "black" and "african american" or "hispanic" and "latino," etc.
Subject headings are library tags you can search by to find resources categorized by topics. In the library catalog, you can see an item's subject headings in its detailed record and click on those to search for more related resources. Here are some of the most common subject searches you could try for diversity topics: