Put a standard boolean pushbutton control on the front panel. Show your tools pallette and select the coloring tool at the bottom. Go to the pushbutton and point at the dark led triangle on the right side. Right click and the coloring window will come up. The bottom left shows the current color that you selected. It will say LED OFF. Now move to the grey portion of the button and right click. The bottom left box should be colored grey 3D object. Move the cursor to the USER row and find the LED OFF color. Left click and the button will change colors.
Now change to the operate tool and push the button to the ON state. Repeat the above procedure using the LED ON color from the USER row. This will still have the triangular LED present on the right side. If you want to reomve this you need to Right click on the control and select advanced, customize. Click the wrench. Select the smallest white box with the LED in it. Then go to the toolbar button second from the right and select move to back. Click the tweezer toolbar button. Save this custom control and select replace in original vi.