Here are some recipes for you:
Red-6% potassium chlorate, 65% potassium nitrate, 25% sulfur powder and 4% carbon powder.
Green-potassium chlorate 27%, barium nitrate 55%, sulfur powder 14%, and carbon powder 4%.
Yellow -62% potassium nitrate, 10% sodium nitrate, 24% sulfur powder and 4% carbon powder.
Purple-33.3% (one third) of potassium chlorate, 33.3% (one third) of potassium nitrate, 23.8% of sulfur powder and 9.6% of carbon powder.
Blue-potassium nitrate 69%, sulfur powder 15.5%, antimony trioxide 15.5%.