Provide your child with a simple outline of a body. You could use a cookie cutter as a pattern.
Let your child select from markers or crayons. Suggest that they color in the parts of the body, using different colors, that represent their feelings. For example, ask them what makes someone feel sad. Then ask them to name what color sad would look like. Perhaps they'll say blue is the color they think of when they're sad. Have them use the blue crayon to color in the part of the body that feels sad.
With young children you can expect them to be able to identify four feelings:
Happy, Sad, Mad and Scared.
A variation of this activity would be to bake cookies using the body shaped cookie cutter and use different colors of frosting to identify the feeling colors.