Hi @Angelika Deutsch and welcome to the community!
Unfortunately, this is not possible natively and I'm not sure whether any marketplace apps can provide this. What I've done in my environments is preface the queue name with an emoji. For example
🔵 Team X
Hi @Angelika Deutsch
Welcome to the Community!
I second Mark's answer, you can use an Emoji instead as a workaround, since this is not natively configurable. If your instance is a Data center version, you can explore third party app - Color Queues for Jira Service Management from Atlassian Marketplace.