Allow changing colours of transformers

Hi there, I like the idea of being able to look at a workspace and seeing easily what transfomers change attributes, which change geometry, which filter etc. To do this, it would be nice to change the colours of transformers, so I could have say green transfromers are filter transfromers etc. I could add annotations to the top of these but it becomes a bit cumbersome. If you can rename transfomers, changing their colours should not cause any unintended issues.