Signing: To sign purple, make the p sign (a fist, extending the thumb and the middle finger, with the index finger extended and bent down ninety degrees). Take your P sign and shake it around in front and to the side of your body.
Color signs are easy to remember because they are often the sign for the letter shaken slightly in front and to the side of your body.
Usage: You can teach the colors with more advanced signers by making a series of solid color flash cards and going through while demonstrating the sign.
Flash Card: Click the link to view the Purple Baby Sign Language Flash Card. The flash cards are printable and available in both U.S. Letter and A4 sizes.