You can expand, or collapse cells to get a better sitemap preview and clear up space.
Each cell that has its child pages contains small arrows at the bottom page cell border.
To expand the cell to see its child pages, click the small down arrow at the bottom cell border.
To collapse the cell, click the up arrow at the bottom cell border.
If you want to collapse/expand all pages on your sitemap at the same time, just use the Collapse All or Expand All buttons on the toolbar