You have probally seen some of Lexy's videos, but if not then check these two out.
You can see she likes floral yoga pants. She has a link up on her site where she showcases the leggings which are created by designer Kelly Nishimoto. You can check them out here.
Here are a few styels that are similar. What you are looking for is a low leg, neon style floral design.
These ones are Betsey Johnson designed.