It would be a long story to establish relationships with all the Signs.
First, there are Four Elements:
Fire: Aries, Leo and Sagittarius.
Earth: Taurus, Virgo and Capricorn.
Air: Gemini, Libra and Aquarius.
Water: Cancer, Scorpio and Pisces.
Secondly, there are Three Status for each Element. The first is Cardinal Signs (in french) and is in relationship with Aries, Cancer, Libra and Capricorn. The second is Fixed Signs and goes with Taurus, Leo, Scorpio and Aquarius. The third is frequently called Double Signs and is related to Gemini, Virgo, Sagittarius and Pisces.
In fact the Twelve are Four Elements by Three Levels.
Also, you have the so called Masculine Signs, which are the Fire and Air Signs; while the so called Feminine Signs are the Earth and Water Signs. So the Twelve are Six Signs for each Two Genders.
It would be hard though to attribute a specific color for each Sign. It would be a nice goal from you if you wanted your Quest to teach some basics of Astrology. But it would be also very time consuming before you get to the point.
Since I play Zelda Quests for fun, please release your Quest as soon as possible. I have been waiting for that one since you annouced it around Christmas time.
TIA