An obvious one. Have participants find something in the room that contains the colour they are/feel. Even better if you can get the three primary colors in tempera paint (red, blue, yellow) and have them mix their own paint to accurately reflect their disposition, and explain. It's messy and takes a bit of time, but with organization, it is beneficial. Another less messy alternative is to go to the local paint store to acquire a collection of paint swatches.