I need a legal e-signature printout and there is no obvious way to do it

When electronically filing a tax return, your e-signature is the 2018 AGI entered which verifies your identity based on the information in the IRS database.  There is no physical signature on an e-filed tax return.

Sign and date the copy of the tax return that was printed if someone needs a signed copy of an already electronically filed tax return.

Self-prepared tax returns do not have a signature authorization page.    That is only for paid preparers.     TurboTax only provided a Electronic Postmark page that should be part of the PDF file for printing all forms.

Your electronic filing page shows that.  When you e-file, there is no physical signature on the Form 1040.  If someone like a lender etc. wants a "signed" copy of your return, you can print your return and use a pen to sign it on the line that says "Sign here."

• Sign back into your TurboTax online account 
• Scroll down and click "Add a State"  (This is just a way to get you back into your tax return)
• Next select "Tax Tools" (left column) and then "Print Center"
• Select "Print, save, or preview this year's return"
• Check the boxes for your Federal and State returns (this will open further options)
• Choose to include the Government and TurboTax worksheets 
• Then click "View or Print Forms".
• View the E-Filing Instruction Sheet (should be first)