Answer:
First of all there are two different colors of unroasted coffee beans. There are green coffee beans and there are arabica beans. While arabica type beans are much more popularly sold in stores. This is because arabica coffee is cheaper to produce.
When judging a coffee by it's color in terms of roasting there are many different options and flavors. There are light roast, medium roast, full roast, or double roast. The color of these beans get darker the more they are roasted. Medium roast coffees have the most balanced flavors than the lighter or darker roasts so these would typically be more appealing in taste.