Have you gone to the HP website to look for Windows 8 drivers for your All in One? This page should be the correct one for the model that you listed. Just choose which version of Windows 8 that you have to get the correct driver.
I found the download page by searching for "HP 7310" in the Windows Compatibility Center which shows that the printer/scanner IS compatible with Windows 8 and gives the link to the driver download page.
Hope this helps,