WARNING: This page is about a different car, the 2004 Volvo S40, 2003 Volvo S40, 2002 Volvo S40, 2001 Volvo S40, and 2000 Volvo S40. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Drain Valve And Coolant Reservoir Cap
Courtesy of VOLVO CARS OF NORTH AMERICA.
Remove the expansion tank cap
Open the drain cock on the right-hand side of the radiator
A hose can be connected to the drain cock to collect the coolant