Graph display powerered by Cytoscape.js
The underlying algorithms behind the term generators can be found here (in Haskell!).You might need to be patient for larger values of n and k while the maps are drawn. For n > 10 be prepared to wait a while, or until the universe collapses!
For larger terms, you may wish to disable map generation to speed up the process a bit.
Draw maps (costly)
Use de Bruijn notation