ColorSync support
OmniGraffle Professional supports Apple's ColorSync technology, which tries to keep colors as accurate as possible when viewed on any ColorSync-compliant display and when printed on any ColorSync-compliant printer.
ColorSync is OmniGraffle's fourth preference pane; you can get to it by choosing Preferences from the OmniGraffle menu.
Select the Use color profiles checkbox to turn on OmniGraffle's ColorSync support. OmniGraffle will embed color profiles in the documents you save, and will try to read color profiles from the documents you open. A color profile helps ColorSync-compliant software and hardware display the document's colors accurately.
You might receive documents saved with different color profiles than the one you are using. Use the pop-up menu to decide what OmniGraffle should do in such a situation. Select Preserve original to leave the color profile in the document as it is. Select Convert automatically to translate the color profile to match your own defaults. Select Ask when opening to have OmniGraffle present you with a choice each time you open a document with a different color profile.
Default Profiles shows the color profiles you currently have set up in the system-wide ColorSync preferences. Click the button to open these preferences, where you can change these profiles to match your hardware. These profiles are the ones that will be embedded in documents you create.
Note that you can manually set and convert color profiles from the Format menu, thereby overriding these defaults.