Hi:
Intel did not develop any graphics drivers for PC's with the Kaby Lake processors, except for W10.
The rest of the W7 x64 drivers from the 15t-ay000 support page should work.
https://support.hp.com/us-en/drivers/selfservice/hp-15-ay000-notebook-pc-series/10862300/model/11528...
The only driver not on there would be the USB3 driver, which I have included below.
This package contains the Intel USB 3.0 eXtensible Host Controller Driver for supported notebook models running a supported operating system.
http://ftp.hp.com/pub/softpaq/sp74501-75000/sp74851.exe
Now, I helped this forum member get the Intel graphics to work by modifying a graphics driver.
See the discussion below and he said to just follow that other person's instructions and modify that driver and run it.
He said the graphics adapter would be called and Intel HD 520, but it worked just fine.
https://h30434.www3.hp.com/t5/Notebook-Operating-System-and-Recovery/Cannot-install-win7-64-pro-in-h...
If you can't get it to work, I suggest you reinstall W10.