Your bag will be collected by LX's baggage agents and recorded as OHD at ZRH. I would guess Swiss port is the handling agent. The bag should still be with the agent once you get back to ZRH unless they are very proactive and forward it to GVA on review of your itinerary.

On your return to ZRH you will have to contact the handling agent to arrange to collect your bag. You will need to check they will still be open (the Swiss aren't that 24/7!) before you attempt this! You will also have to hope they do not insist on delivering it to you as you may then have a wait.

You will also need a story explaining what happened otherwise they may charge you a fee! The agent is not a provider of baggage storage and you are wasting their time and warehouse space.

I would not recommend this as there is a small chance it will not go to plan and there is left luggage lockers at Geneva CFF anyway so it is no hardship to store your luggage there.