I'm surprised by this, but both Alessio and Optimization Process needed this.
This should probably be done by making the tiles in the diagram grey or beige (or both), colors that do not exist in this many gradations in the actual tileset. Or by coloring the tiles with a patchwork of colors that don't quite line up with the tiles themselves to make sure it's clear that we're not saying that any particular tile is any particular color.
(this is one of the areas in the game where I actually didn't mind which way you did it and I want people to experiment with both ways. If you play the same map repeatedly, do you learn its nuances? Do maps have personalities? We just don't know yet! But probably not since your relationship to the map (your umwelt) changes so much per session.)