You might need to render your site in a single PDF or image, but if your site is too long to fit into usual document sizes follow the below instructions.
To print a long vertical site into a single file (PDF, image):
1. Load your site with Google Chrome.
2. Click File > Print or you can press Control + P (for Windows) or Command + P (for Mac) on your keyboard.
3. Use the settings shown below for Destination, Sites, and Layout.
4. Click + More Settings, and use the suggested setting settings below.
5. Depending on the length of the site, you can change the values for Paper Size and Scale.
6. Once you're happy with the fit, click the Save button on the upper side of the left editing pane.
The site will be saved as PDF, apparently, and you can use 3rd party applications to render it in a different format, like an image, or to edit the file further, such as in terms of its cropping, dimension, etc.