In the DMS most of the windows only support a very small, compared to the Enhanced Program Editor (which is one reason it is called Enhanced), color set.
There should be two macros with code that show how to change/set/ colors for the Log, Output and other windows. Look in your SASFoundation/9.4/Core/sasmacro folder for the macros Dm608clr.SAS and Dmcolors.sas.
Warning: These macro reference some windows that are no longer in much use and can generate errors. Plus not all windows accept all options based on their purpose. The DM 'LOG' entry in the Dmcolors.SAS probably has the most options.
PS: The DMS runs under multiple operating systems. So generally the things that you can address ignore operating system settings.