Dude, its almost an airport change. The int and dom terminals - though connected airside, are a fairish drive (about half an hour or so, given mild traffic) from each other. A bit faster when you use the airside courtesy coach rather than going out and getting a cab.

The CO people will have staff at the domestic terminal to assist you in your transfer, based on what I saw the last time I flew CO out of BOM rather than AF out of MAA.