You don't need the cat5 cables; RPi3 has WiFi built in. Just use a router and you're all set. Set up your first one with SSH enabled and WiFi enabled for your wireless network. Then, clone the card for the other 7 systems. They should all show up on your WiFi router and you can SSH to them as needed.
I've got 5 RPi's of various generations. I could be accused of being a "Cat Lady" of Raspberry Pis!