On the left is the device main screen, from here you can access your folders/contexts. You can change between context and folders in the preferences page. If you long click on a folder it will allow you to edit the folder/context. One of the options is to set a color value for the folder/context. You can also rename the folder/context and the change is synced with your toodledo.com account on next sync.
On the right is the device task screen.