Several ways:
1) Change the location of the chart to have its own sheet. Do this by right
clicking the chart, go to "Location" and putting it on it's own sheet. Then
you should be able to print it by itself without any white stuff.
2) Make sure that the page breaks are defined well. Go to View -> Page Break
Preview . From there, you can move around the blue lines to determine your
page breaks. Then, when you're printing it, make sure that you choose only to
print the page that your chart is on.
Those are the easiest ways, anyway. I'm sure there are more, I just can't
think of any right now, sorry! >_<