A family of Microsoft relational database management systems designed for ease of use.
Thadeu,
There are a few things you can do but keep in mind that if you reduce the diagram too much, it may not be readable.
First, you can reduce the spacing between boxes. Go to Format/Format group/Layout icon. Adjust the row and column spacing.
Second, adjust the scaling by going to File/Print/Page Setup/Page tab
Third, make sure you are not printing blank pages. Go to File/Print/Page Setup/View tab
Fourth, consider collapsing the outline to only show summary tasks, or perhaps collapse select summaries.
Hope this helps.
John