Simulation tools offer a low barrier to entry and enable testing and validation before field trials. However, most of the well-known simulators today are challenging to use at scale due to the need for powerful computers and the time required for initial set up. The OpenUAV Swarm Simulator was developed to address these challenges, enabling multi-UAV simulations on the cloud through the NSF CPS-VO. We leverage the Containers as a Service (CaaS) technology to enable students and researchers carry out simulations on the cloud on demand. We have based our framework on opensource tools including ROS, Gazebo, Docker, and the PX4 flight stack, and we designed the simulation framework so that it has no special hardware requirements. The demo and poster will showcase UAV swarm trajectory optimization, and multi-UAV persistent monitoring on the CPS-VO. The code for the simulator is available on GitHub: Https://github.com/Open-UAV.