Your concern is if the engine overheated or did not. So the loss of radiator coolant is not as important as the Engine heating up beyond the limits. One easy way to tell is if someone looked at the temp gage to see if it went to max and stayed there! Did you get any other indication? like the "Check Engine Light"?
If the gauge read full and other lights came on and you ran it for all those 56 miles in this condition, you may have caused a problem. But not necessarily. My previous 760 Turbo Wagon (in 1995) had overheated (thanks to my wife, also!) and temp. gauge read full, she drove 10 miles! Although I was concerned, I did not have any problems and the car drove fine. No problem with mileage or oil consumption. So check if temp. gauge was noted, check oil and fuel consumption or get mechanic to check. I think, you are okay.
Imagine if this had happened to a non-Volvo engine?