Alrighty you got yourself the sketch, now it's time for colors! There are several approaches to going for colors. You could go off of powers, names, personality or even occupation.
Whenever it comes to powers, we often associate different colors with different abilities and symbols. If a character has ties with nature, they benefit from having greens and browns as a color scheme. If their power has something to do with magnetism, blues, reds and whites are the way to go. Fire benefits from reds and oranges, you get the picture.
Names may be a bit tricky if it's a name you would give to a human being like Robert, Mary or Alex. If you name it after an object or an adjective that describes an object such as "Pumpkin" or "Rusty", you could get away with color schemes inspired by the namesake. Taking a word and translating it to another language is a popular option and could benefit greatly from this. The Japanese word for heart, "kokoro" could offer reds, whites and pinks as hearts are oftentimes symbols of love while the Spanish word "Azul" translates to blue, making a character benefit from a blue color scheme. You may also utilize an alias or a nickname that the character adopts for themselves. A character nicknamed "Bumblebee" would sport black and yellow colors.
Colors are a shorthand for certain symbols. We often associate red with hot while cold is blue. Yellow can be shorthand for fear or joy while purple is shorthand for royalty. Different variations of colors can also be indicators of personality. Pastel colors would be perfect for innocent, sweet or shy character types. Muted colors would be perfect for brooding or modest types. Dark colors often provide an air of mystery and bright colors often indicate a cheerful or loud type of character.
When you think of certain jobs, different outfits may come to mind. They often adhere to varying dress codes and that includes the color of your outfit. Construction workers will be seen wearing orange, hunters are often seen wearing muted greens and browns, and fast food workers often sport bright colors that go with their restaurants. This can apply to hobbies as well. Bakers may wear bright or pastel colors to indicate confectionaries they craft for example.