I recommend colored contacts from a Halloween store. There's a great website if you're just looking for one time use I could find with google. Magickcannot do anything like changing your eye-color. If I were you, I would take a look at what magick can and cannot do.
Here's my general rule of thumb:
If it cannot be done without Hollywood special effects, it cannot be done.
No physical transformation, no fire balls, no invisibility, no summoning a dragon to eat your parents.