Physical appearance descriptions are only superficial. Describing hair, eyes, skin or clothing colors tells the reader nothing about internal motives. However, assigning specific colors to important characters is a good shortcut for coding their personality. You can remember what major motivation you gave each character by using the color associated with it for a physical feature or possession the character wears.
To connect traits to colors, I’ll refer you to the work of Swiss Psychotherapist Max Lüscher. I used the Lüscher color test as a kind of party game in college (Even though the Amazon site discourages that.) I’d ask the other students to put the eight colored cards in their preferred order. Then, I’d read directly from the manual about their overarching goals, what they used to achieve goals, and what they were suppressing. The traits associated with colors are generic enough that many different people can see themselves in some of them. So, the other students generally agreed with my observations.
For example, blue stands for “depth of feeling,” evidenced by a desire for peace and tranquility. Depending where this blue card is placed, peace can be the goal, or peace can be used to achieve another goal, or it can be what the character is willing to sacrifice. You do not have to choose a color for each of these positions. You could use two colors for this first position. However, the more work you are willing to do, the more depth your characters will have.
These are the eight basic colors and their interpretations:
Blue: The character prizes tranquility and exhibits a calm, tender behavior. Being passive is their weakness.
Green: Indicates an elastic will. The character is persistent, confident and in control. Their weakness is being over controlling and assuming possessions equal success.
Red: Action, excitement and sexuality are the goals. This character is competitive and aggressive, sometimes extremely aggressive with little care for how this affects others.
Yellow: The character seeks exhilaration and expects the situation to get better. They can be spontaneous, or launch into action with no planning, or run around and achieve absolutely nothing (like a chicken with their head cut off).
Violet: Identifies esthetic values. The character prizes being charming, enchanting and culturally sophisticated. Their weakness is being unrealistic and depending on wishes to come true.
Brown: The character is sensitive to bodily senses. They prefer simple comforts. They may be in touch with nature and their natural side. They may also be lazy.
Grey: This color indicates non-involvement and concealment. What the character conceals may be based on another color in the list of motivations.
Black: If this is a character’s first choice of color they seek to fade into the background and hope to achieve this by renunciation, surrender or relinquishment of valued things. You must also determine what these are.
In conclusion, don’t expect the reader to guess the traits of your character just because they always wear a necklace with a blue sapphire or have baby blue eyes. The colored item is there for you to recall the traits.