Placing the swap file on a different (usually slower type when you are using Host Cache, or a faster one (SSD) if not) disk is a best practice as described in the performance best practices document (http://www.vmware.com/pdf/Perf_Best_Practices_vSphere5.5.pdf - page 28). The default location for the swap files is in the same folder as the VM, but you can override this on a host (or cluster basis) under Configuration -> VM Swapfile location and choose a specific datastore. For the cluster, this is located in the cluster settings.
However, this is a bit more advanced stuff and needs to be thought through before changing this and it seems to me like you do not need this now. So, your VM swap files will be stored in the same folder as your VM files, but do note, that a swap file is equal to the memory assigned to the VM, minus any reservation. For a 8GB VM without any reservation, an 8 GB swap file (thick) will be created, so you lose 8 GB of capacity. Since SSD's usually are not so big as SATA or SAS disks, you might want to keep this in mind.