In the new version of the software, isomorphic graphs are automatically removed while processing. This way the generation of all graphs/maps is a lot faster … not as plantri but faster than before.
Download it from here: https://github.com/stefanutti/maps-coloring-java
Using it, I generated all simplified graphs, in graphml format, up to 18 faces:
Here is the video on YouTube:
Four Color Theorem 