Cute, being an intangible adjective sign, is best left to more advanced signers. The most popular way to teach it is to use it as a term of affection with your baby. Then expand its use to things you see with the baby during your day, like the family cat or a flower. They probably won't understand what it means at first, just that you are happy, and that makes them happy.
Cute is best taught through providing many real-life examples. Start by referring to just a few things as cute, then expanding your usage as the baby starts to learn the sign. At the expansion stage, you can add the cute flash card as a further example of something that is cute.