When dealing with a comment like this, it's important to remain calm and respond in a way that promotes understanding rather than escalating the situation. Here’s one way you might respond:
"The idea of categorizing people by 'color' is an outdated and overly simplistic way to view human diversity. People come from rich and varied cultures and backgrounds, and reducing them to a color label doesn’t do justice to who they are. It's better to engage with people based on their individual identities, experiences, and humanity rather than outdated stereotypes."
This response addresses the underlying issue without being confrontational, encouraging a more respectful conversation.