Are artificial colors safe for kids?

No. Kids are designed to be enticed by colorful nutritious foods such as a rainbow of fruits & vegetables. Artificial colors overwhelm and hijack this attraction, luring them to processed foods. And the dyes themselves, often made from coal, have been linked in some studies to problems with learning, attention & behavior. Risks vs benefits? With no benefit, the dye's small risk is unecessary.
No. Simply put, no good health outcomes have ever been associated with artificial coloring. While the data is limited regarding adverse effects, some studies have demonstrated negative neurodevelopmental effects (hyperactivity) in children exposed to artificial dyes. Would put this under the heading of the precautionary principle - avoid until proven safe.