Gently place eggs in single layer in large saucepan. Add enough cold water to cover eggs by 1 inch. Cover. Bring just to boil on high heat. Remove from heat. Let stand 12 minutes. (Adjust time up or down by 3 minutes for each size larger or smaller).
Pour off hot water and rapidly cool eggs by running them under cold water (or place in ice water) until completely cooled.
Mix 1/2 teaspoon vinegar and drops of food color in a small container to achieve desired color. Repeat for each color. Paint hard-cooked eggs with small paintbrush or cotton swabs. Allow eggs to dry.