As perhaps one of the few people to actually like the Xeno colors better 
for Homeworlds, I prefer thee assignment:
Red	Orange - Fire and the Sun are both orange and both hurt if you touch 
them :)
Blue	Purple - Purple's wacky and grants the mercurial power of Trade.
Green	Cyan   - Cyan reminds me of water, and water is necessary for life to 
thrive and grow
Yellow	Clear  - I think of this as a speedy General Products hull, since 
they're totally clear
This also works best in my mind since it follows the color wheel pretty 
closely--Red is close to Orange, Blue to Purple, Green to Cyan, and Yellow 
is the lightest color, hence substituting with Clear makes sense. White 
could work just as well, but I tend not to play with Opaque pieces in 
Homeworlds for some reason.
-- Josh
--On July 24, 2006 9:57:25 PM -0400 Ryan McGuire and Kerry Breitenbach 
<kerry_and_ryan@xxxxxxx> wrote:
To head this problem off at the pass, I'll put MY scheme for assigning
Xeno colors to Homeworlds powers on the table.  Rather than trying to
asign Xeno colors to Rainbow colors, I figure it makes more sense to make
the Xeno power assignments without regard to the Rainbow set:
  Move       Clear    As in "This ship is going to CLEAR out of this
system."
  Trade      Orange   Because it looks like gold.
  Construct  White    Like the white building materials of Portland,
England and/or the Inuit.
  Attack     Purple   Like the bruises you'll have when I'm done
attacking.
The other obvious option is to assign Xeno colors to similar Rainbow
colors. Maybe...
  Red     Orange
  Blue    Purple
  Green   Cyan
  Yellow  Clear or White