Hello Ezequiel, how are you doing today?

There is no way, at the moment, to actually change the color of the card but you can update labels using automation. 

You can choose the event you wish, a condition as well if it fits, and then use the action “update a field’s value”. 

There you can select specific labels -that you have created in your process- for your case.

For example:
 

Let me know if it helps! :)