Take diff colors from color scheme

Change-Id: I706612a8f89917cb57b7d1e9ecebd86b3f4bcc8d
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@digia.com>
Reviewed-by: Eike Ziller <eike.ziller@digia.com>
Reviewed-by: David Schulz <david.schulz@digia.com>