I heard different children have different responses to colors.
I am not sure if it's something that can be "trained".
My girl was very sensitive to colors, by 18 months she can say mandarin, orange, purple, blue, black, brown, grey, yellow, pink, gold, white, green, maroon, both English / Chinese and loves colorful flowers, rainbows and books. She can even site her favorite color is green.
Perhaps what helped was I showed her many picture books, took her to the gardens and outdoors, vegetable markets, colored crayons. I also have artwork and paintings in my home (for decoration), and I chose toys with different colors (not limited to pink just because she is a girl) I guess those things got her really interested in colors. Maybe you can try?