Grouping by tag

I am trying to visualize ping-times for openvpn-clients. in influxdb i have for each connected client (stored as tag) ping times (min/max/avg stored each in a field).
in the graph i have three queries to display each field. that means each client (tag) has 3 values. when i want to filter i need to select 3 statistics from the legend.

how can i make it easier? i just want to have all clients listed in my legend and when selecting a client i want to get min/max/avg values displayed.