Well, a lot of people make the same mistake with you for their carelessness. Anyway, you should know such coloring or something is a chemical product which is highly irritative to your fragile eyes. Therefore, you need some immediate measures to deal with it. Try to wash your eyes with plenty of salty water, then get some eye drops to help. If necessary, try to visit an eye clinic for treatment.
What you should do is to flush your eyes with lots of water, then go to see a doctor. Actually, you shouldn't put stuff like that into your eyes. It would probably harm you. First, it would not change your eye color if you wanna change color of your eyes through that way. Second, it would likely cause an eye infection.
Food coloring is the chemical material which could irritate eyes terribly. You will have eyes burn, red and pain. Calm down, and get help from someone. Because you can barely open your eyes, have someone to pull you lid and use running water to wash the food coloring out of your eyes. Keep doing this for about 3 minutes until the burn is gone off. You can put some ice on your lids, close your eyes and take a rest. Because the food coloring is a kind of chemical, I am afraid it will cause other problems to eyes. So the best suggestion for you is that if you still feel very uncomfortable with eyes, go to hospital. Doctor could give you professional investigation, suggestion and cure. Once damage to eyeballs is done, we may probably lose our sight which is terrible for everyone. Please take good care of yourself.