If you are doing the solid green that PTs used when moored alongside a tropical canopy (like the 109 most likely had when she was rammed) then the best known guess is a dark / forest green. For what it's worth given that images don't always portray the true color you can see a bit of the color in the images here: http://www.pt103.com/PT_61.html
Then there were the boats that according to the CO were painted in colors locally sourced like this shot of PT 61. The entire crew had a say in its tint although as you can see from the wetted deck it faded a lot from the time of its painting:
: Who makes the most authentic colors for USN
: Elco PTs?