Here are some examples of physical and logical diagrams
An Example layer 3 (logical) network diagram of 198.32.128.0/22
An Example physical subnetwork 198.32.128.0/23
An Example physical subnetwork 198.32.128.192/30
An Example physical subnetwork 198.32.130.25
An Example of textual documentation
For logical diagram you need to include: 1) routers (as boxes) 2) networks (as ovals, or as a single line for point to point). Inside the routers put a name. Inside the network ovals put the full network and netmask (use /XX notation for netmask).
For each link from a router to an oval put a label near the interface name and the *significant* portion of the assigned IP address. IE, if you are connecting to a /24 or smaller (size wise) you can just put the last octet of the connection. If you are connecting to a /23 or larger you will you may need the last 2 (or even 3 octets) to be unique. For point to point links put the network number on or nearby the line. Include a legend of the symbols you use for routers and subnets. Use a dashed line to delineate different physical sites on the diagram. Include a subnet summary
You will have one physical diagram for *each* subnet even point to point subnets though those will be quite simple, just a line between two routers. For the physical diagrams you will have routers and switches and other pertinent layer 2 or layer 1 equipment. Each device will need specific symbol and a legend will need to be included.
For the routers you will only show the interfaces that are one the specific physical subnet you are documenting. You will label the interface with its name and IP address.
For switches/repeaters you will want to label each port with a appropriate port number. For "access" ports that face only workstations you can list them together and label as a group.
Each device (switch, repeater, etc) that has a IP based management address will need to be labeled with that address.
Be sure to label (and include a legend) for any different types of media you choose to use. Even cross over ethernet cables between switches must be distinguished from straight through ethernet cables.
Make a note of the available IP addresses on the network that you can assign to stations. (IE the addresses you have not used for router ports or switch management)