Start the day off with a color hunt. As I type this, St. Patrick's Day is approaching, so let's use green as our sample color. You tell your child, "Today, we are learning about the color green." Then hold up something green, "This is green. Can you see anything else in the room that is green?"
Then go on a hunt through the house looking for green items. You might have pictures, pillows, paint, plants...you will be surprised at how much you have. You can take your hunt outside...if you live somewhere with green outside right now. Boo.
I always have the whole family wear our color we are learning about that day if possible. Wear green shirts, socks, underwear...be sure to point out as your child is getting dressed everything with green on it.
I also like to try to eat food that is the color of the day. So for green, we might have broccoli, a salad, or celery. If you like to dye food, you could have pancakes colored green. You could make cupcakes and dye them green and/or dye the frosting. Dye your milk green and make green cookies. Have green Jell-O and green pudding.
The point here is to point out to your child that the color of the day/week is all around her. Show lots of excitement about it, and she will to!