All nodes of the selected color will be selected in the Node Graph.

• Select a node
• Edit -> Select similar -> Color

• All nodes of the same color will be selected in the Node Graph.

• Copy 'selectSimilarByColor' folder in your .Natron folder.
• Add following lines to your 'initGui.py' file, where <path> is the location of 'selectSimilarByColor' folder.

from <path>.selectSimilarByColor.selectSimilarByColor import *
NatronGui.natron.addMenuCommand('Tools/Edit/Select similar/Color','selectSimilarByColor()')