If you turn on the Print List" strategy you will find the print icon in the dropdown menu above the list displayed in the main view, for example, Today list:

Click this icon to open up the print overlay. 

In the print overlay you can see your list and expand/collapse any nested items to make sure you are printing exactly what you want. 

Once all the items you need are showing and you are ready to print, click the print icon in the very top left to get to your computers print dialog. 

Change any settings you need here and click print. 

You can currently print 

To print a project or category, go to the fullscreen project/category view and click the print icon at the top right of your task list.

To print a Smart Lists, either go to the Smart List overlay (through the main menu) and click the print icon next to the list.

Or if you want to see the Smart List first, you can open it in the main view using the Sidebar and then print it using the same dropdown menu as shown on the first screenshot.