TurboTax will automatically save your return when you sign out. Just make sure you will remember your user name and password. To sign out, click Tax Home and then Sign Out.
You can also save your return as a PDF before filing. Here are the instructions. https://ttlc.intuit.com/replies/3333012
Please refer to the information below to download/print a copy after filing. https://ttlc.intuit.com/replies/3301525