Hmm...it might be interesting in the four bottom boxes to distribute four of the more ubiquitous geometric symbols that fit nicely into an even square space like that, and then reserve the top two portions for something a little more organic?  I had a layout idea using the Pentacle, Septagram, Triple Moon, and the Unicursal Hexagram...whipped up a little (admittedly quite ugly) picture...not that I expect you to do this, but hopefully it might inspire some ideas?

 

 

Excuse the colors, pixelation, etc...was just kind of a rush job to get the idea down.  I guess two good issues to keep in mind would be a) what colors symbolically/aesthetically fit the symbols the best and b) is there any reason for a preferred ordering of the symbols?

 

I'm interested to see what ideas other people have.