The way I prefer to do it in gnome-terminal and konsole (both can do it) is to set up sessions that have the color info in the session for the terminal, and the command to start the session is an ssh command. In konsole, theoretically, you can bind this to a keystroke but there is a long-standing issue with that where it can't seem to persist across restarts, and has weird problems sticking even within a session. But when it works it's convenient, especially when combined with SSH's ControlMaster.