If you need to create a map within the American Factfinder (Census) and you need to customize (change the basemap, color, etc.), after you have created the map itself using some of the following data tools:
First, create you map from the Tiger Web. Reference their guide, How we map as well as Creating a Thematic Map Using TIGER/Line Shapefiles.
You can then select your basemap (2018 data is now available)
For help in using the products, see these tutorials: