If it was a smaller page designed for the booking process rather than a big electronic board I'd recommend just displaying one day at a time, with a dropdown to swap between them. But since this is designed to give an overview, my recommendation would be something like this:
download bmml source – Wireframes created with Balsamiq Mockups
The colour gradients represent how many rooms are free: dark colours mean few rooms, lighter colours mean more rooms. Some sacrifices must be made to reduce the clutter and I think the least important fact is which room is available. A different colour scheme may work to, from red to green for instance (but it could be unclear to colourblind users - not that the current system is super friendly to them!).
I may have it wrong, but I gather that the students look at the board to check if a room is available at their chosen time, and then book it on their separate device. They can see if a room is free at a glance - they don't know which room but it's not relevant until they log on, at which point a more detailed list is displayed.