@mark noble,
Hi Mark,
I would have so they associate the colors with things they can touch, taste, smell, hear... all the other senses they have. Example...
Blue = ice
White = cotton
Pink = sticky cotton candy
Red = Rose
Green = Grass
Yellow = The heat of the sun or simply the sun
A person just needs to use their imagination to come up with things to describe colors to those who cannot see them. What they can do is hear, smell, taste, and touch things in ways people who can see can never imagine.
Have a great day
Rhys