5 Building Network Architecture/Diagram

I'm creating a sample network diagram for a course and have the following requirements:

Each building is about 500 meters apart.

These buildings were wired with Category 3 UTP running 10BaseT Ethernet. (They now need Cat 6 because of 1Gbps requirement)

Mandatory 1000Mbps to Desktops

A connection to the Internet, routers, switches, printers, cabling, PCs, and firewalls.

My thoughts:

Create 5 separate 1 level buildings or representations of buildings

Each has a switch connecting to a central node/switch at a main building (2 stack Cisco switch preferably)

One Network Printer (anything)

Firewall is hardware or software based (located at central switch/node)

I show one Desktop per building representation (any brand)

*Ports and advanced network information are not needed for this diagram, just basics.*

Questions:

How do I show cat 6 cables on this diagram?

Where would the internet go on this diagram?

Where is the router on this diagram?

Disclaimer: All of this is being done with Visio