to my knowledge there isn't any way to state what workspace an event or task belongs to in the calendar, HOWEVER, when creating new workspaces (or editing current ones) you can assign a color to a workspace.
Not only does this place a ball the color of your choosing next to the workspace in the workspaces panel; it also colors the text of that workspaces objects to match the color of the ball.
So if I have a workspace with a purple ball, then in my calendar, all events for that workspace will have a purple background. Also when viewing objects like contacts in "All" view, it states the workspace that the object belongs to and that is also color coded.