Your Apple Macintosh comes with a very cool feature called ColorSync. If you are using your Mac for graphics work, you are probably already familiar with the ColorSync concept.
ColorSync will ensure that what you see on a ColorSync enabled monitor and what's being printed on a ColorSync enabled printer will look exactly the same.
ColorSync support is controlled from the ColorSync preference pane. Use the OmniGraffle | Preferences... menu command to open up the preference panel.
If you enable ColorSync by checking the Use Color Profiles checkbox, the program will save color profile information along with the OmniGraffle document—or ...