It’s not a built-in feature of the plugin. But the chat messages include various classes, so may would be possible to implement a custom solution.
Where do you think it would be easiest to implement, to form.php file?
And which class is actually doing that coloring currently to every msg?
I can’t recommend modifying any core files. But you don’t need to, because the plugin makes it easy to add your own CSS via the setting “Custom CSS styles”. So you can use Code Inspector in your browser to examine the various available class names. And then craft and add whatever styles are needed.
I got correct colors showing for current logged in users, but those colors aren’t global. Only showing ie. for admin only, regular users see still white text
Any CSS added to the Custom CSS setting should be applied to all posts and pages on the frontend. Unless you have Targeted Loading enabled. Make sure that the “Chat URL” setting is blank/empty would be a good idea to check.