FireBrick MAC Graphs

The FireBrick is able to graph traffic for each MAC address it sees.

From the manual:

There is also an option for set-graph-source-mac which causes the session to set a (forward) graph that is based on the MAC address of the source packet, if from an Ethernet interface. The graph is created if it does not exist. If set-graph is also defined then each new session created also causes the speed settings and long term shaper parameters to be copied from the named graph (in set-graph) to the MAC named graph being used. This is aimed at management of open WiFi and the like allowing a named shaper to be defined and a copy of its settings created for each client based on MAC address.

Assuming you have no current outgoing ruleset, create one such as:

<rule-set name="LAN Outgoing" source-interface="LAN" no-match-action="continue">
 <rule set-graph-source-mac="true" action="continue"/>
</rule-set>