goodroi - 1:41 am on Aug 31, 2011 (gmt 0)
Option 1 - Move the color selection to another page
Option 2 - Put the color drop down in an iframe
Option 3 - Write a few paragraphs of unique product description for each page so Google knows the page is about the product and not the color
I'd go with option 3. I think your rankings problem are probably not because you use the word "light" or "blue" too much but rather that you mention the product too little. Good luck.