How do I include graphs in Quip?

If you take some time to play around a bit you may find the solution. For instance, try creating a new document, then look at the suggested templates at the bottom. Usually, I see "Checklist, Kanban Board, Calendar, Spreadsheet" and then there's an Explore Apps. Click that and the first thing on the second row is Lucidchart Diagram. Check out all the apps and play around with the program a bit. You'll get the hang of it. :D

It depends on the kind of graph you are trying to bring in. You can bring Lucid Charts and others in via integration.