These are not the signals you should be wanting a ref to show you.
The signal for a caution or sending off is the same - it's just the colour of the card that is different.
The referee will take a note of the player and then hold the card high above the head with an outstretched arm.
If the player is sent off for two bookable offences, the referee will show the second yellow card before holding up the red card.
It is possible, though, that a player who has already been booked can be shown a straight red card.