To change the color of the department headline, go to:
1. From the Control Panel under 'Master Settings' choose 'Edit Font Settings'
2. Change 'Department Headline Font Color' to the hex code of the color you want to use and press 'Apply Changes'
3. Choose 'Edit Site Descriptions' under 'Master Settings'
4. Press 'Apply Changes'. This will push the font setting changes through to the Department Pages.
That will update all of your Department pages.