DataStudio will print the "active window"

Whichever graph or table or meter is active, that's what will be printed when you select PRINT from the File menu in DataStudio.

To make use of the most "real estate", you might consider setting the printer to LANDSCAPE mode when you print a graph.

You can choose if you want the "header" to print or not - this would have your graph title, the date, and the filename from which that graph was taken.