There's a few ways.
Under Network-wide -> clients, you can filter for "connected to" in the search box and filter for the switch you're looking for. You can also add "port" as a table column.
Another way is to go to the switch itself (Switching -> Switches -> Select the switch), and go to Tools and click "Run" for MAC forwarding table
Another way is to go to the switch port (Switching -> Switches -> Select the switch -> select the port), and scroll down to "Current clients" for the port