It's not exactly the same as the previous version, but there's a "light theme" available that sounds very similar to what you're looking for. To use it:

1. Click on the hamburger menu (the icon with three horizontal lines) in the top-right.
2. Click "customize".
3. In the bottom-left corner, click on "themes", and choose "Light" from the list of options that appears.
4. Click the "done" button in the bottom-right.

Hope this helps!

Update : Here's a more comprehensive project which affects not only tabs but brings back the old "grid-style" options menu. https://github.com/axydavid/FirefoxUI/blob/master/README.md

And It isn't completely possible to use the Australis design with Firefox 57, but depending on what you want, you might be able to customize the UI to look more like the old one:

   This project: https://github.com/wilfredwee/photon-australis lets you have the old tab bar appearance back in Firefox 57.
   You can remove the space around the address bar by right-clicking on the spaces, and choosing "remove from toolbar". 

Note: the example is using the Black Theme in Customize

Please let us know if this solved your issue or if need further assistance.