Cameo Simulation Toolkit: Before you run a simulation consider enabling Auto Open Diagrams under Environment Options -> Simulation. Alternatively, consider using split horizontal or vertical window groups (if there are only a few relevant diagrams).

Whether enabling the Auto Open Diagrams option is a good idea depends on what you wish to view when, and whether you are interacting with the simulation, or just letting it run through (such as when performing a screencast recording of a simulation execution).

If you only have a few Activity Diagrams and StateMachine Diagrams you might instead consider having them all open at once using the split window group facility in MagicDraw/Cameo.