Pair each color with a song. The following songs are nice because each color song has a different tune:
Black Color Song
Red Color Song
Yellow Color Song
Blue Color Song
Green Color Song
Purple Color Song
Orange Color Song
Pair each color with a scent. (The child can even smell the appropriate scent while she sings each color song). Scented markers are great and are available at Amazon.
Black- Licorice Red-Cherry Blue-Blueberry
Yellow-Lemon Green-Mint Orange-Orange
Brown-Cinnamon Purple-Grape Pink-Melon
Turquoise-Mango Dark Green-Apple Magenta-Raspberry
Photo Credit Salvatore Vuono @ freedigitalphotos.net
Here's an example of an approach I used in therapy:
The student sits on the red therapy ball and tosses several red balls into a red bucket as I sing or play the "red song". Then we move to a table and the child colors a picture of a red firetruck using the red scented marker while the "red song" is playing in the background.
Eventually, the pairing should not be necessary, but initially the goal is to help the student associate the smells, songs, etc. with the particular colors. At some point, when the child sees the color green, the song & smell for green should come to mind and this will help them remember "that's the color green."