Now, there is a bit of disagreement on the color system. Basically, everything I look at gives a different set of "colors" to use when representing each sign. The fact that they vary to such an extent usually is the sort of thing that indicates none of them really work. Amusingly, Anna Riva in her book Domination covers her bases by trying to list them all:
Virgo: Gold, black, blue, pink, yellow
Taurus: Yellow, blue, green, red
Scorpio: Brown, blue, red, yellow
Sagittarius: Gold, blue, green, purple, red
Pisces: White, black, green, pink
Libra: Black, blue, green, red, yellow
Leo: Red, green, orange, pink
Gemini: Red, black, blue, white
Capricorn: Red, black, brown, green, white
Cancer: Green, blue, brown, white
Aries: Pink, orange, red, white
Aquarius: Blue, black, pink, white
...as you can see, there is plenty of overlap. Another system is to use the color of the birthstone for the target's birthmonth; or else, just plain white for all of them.
You can buy plenty of ready-made formulas for dressing zodiac candles. I often just use a single-note herbal infusion for this purpose, my system being as follows:
Aquarius: fennel seed
Aries: chervil
Cancer: cinnamon
Capricorn: caraway seed
Gemini: marjoram
Leo: chamomile
Libra: st. john's wort
Pisces: clove
Sagittarius: nutmeg
Scorpio: coriander seed
Taurus: thyme
Virgo: dill weed
This has always worked so far.