Many of the color signs are examples of so-called "initialized signs." Initialized signs use the handshape that is associated with the first letter of the corresponding English word. These handshapes can be useful cues in remembering what the sign means. Often in ASL, several signs representing related concepts are distinguished by the contrasting handshapes corresponding to the first letter of the usual English translations; notice that BLUE, YELLOW, PURPLE, and GREEN differ just in handshape.
Note that some of the color signs are not initialized; RED, BLACK, ORANGE, WHITE, and GRAY are not initialized. Some books on signed English show an initialized version of RED that has an R-handshape. This sign is not widely used in the Deaf community.