I'm working on making VTT maps for the Mysterium in preparation for eventually running this AP, and I wanted to put some simple mosaic designs on the classroom floors on level 1. Obviously the white/dark mask of Nethys is one, but I'm not a big Golarion buff so I'm not sure what might be appropriate for the other three. Are there some symbols of related gods, or symbols related to whatever kingdom the Mysterium is located in, or other symbols for knowledge/learning/Nethys?
I would say just use black and white mosaic designs, or anything dealing with angels, as angels seem to be common theme for the Mysterium.
If you use a photo editing program (I use LunaPic since it is free and online), you could use Filters and Effects to make black and white art and make them mosaic looking.