I am not aware of this being visible in the GUI.
If nothing else, this is logged into the server log. You'll find it at <TeamCity Server home>/logs/teamcity-server.log (it may also have log-rotated to e.g. teamcity-server.log.1 or been cleaned up completely). In that log, search for a message in this format:
[2015-09-24 06:49:02,275] INFO - tbrains.buildServer.ACTIVITIES - Build queue order changed by 'dylanbob' (Dylan, Bob: Highway 61), old order: [Queued build }, item id=474526}, Queued build }, item id=474524}], new order: [Queued build }, item id=474524}, Queued build }, item id=474526}]