dots

Go ahead and spell "D-O-T-S." Or you can use a "C" handshape to show big dots on your shirt. Or you can use an "F" handshape ( classifier "F" ).
Or, after spelling the word "D-O-T-S" you could use an index finger and a poking motion to show where the dots are.

DOTS: as in great big dots on a clown's suit: Use a "C" handshape to show where the dots are.
:

You can show a bit smaller dots using an "F" handshape:

Note: if the dots were on a wall, you'd do the dots out in front of you or in the direction of the wall.