While most of the examples show just 5 fabrics, here is a link that uses more:
http://www.blankquilting.com/QuiltSe...icGallery.aspx
I think you could make a green block and a purple block and maybe lay them out is rounds. example a green block in the center surrounded with purple blocks and the more green around them.
Or you could mix them all up within the blocks and the setting.