Make a copy of the new made layer and press on
Alt button to erase the unnecessary things and set the black color.


The
Opacity on the layer should be of
50%.

Now we should merge down in a group all the layers containing the button.
Then copy the new made group four times and make use of the
Free Transform option to change the parameters, like it is demonstrated in the next image:

Take the following instrument

and represent the PLAY symbol colored in black.