Another idea that might work (you might want to experiment with a few pills to be sure) would be to use the same concentration, but use some sort of aerosol spray that could spray a very fine mist. That way you could color quite a few at the same time. I’d make sure I used baceriostatic water, and soak all the the equipment that will come in contact with the pills and the foodcoloring in a sink full of hot water with about a tablespoon of bleach added, then allowed to air dry. That’s the approved method by our local health department for restaurants for their cooking utensils. What little bit of bleach you use will kill most germs, and will evaporate when air dried.