TradeStation EasyLanguage Quick-tip 80 shows how to to change colors that have been 'hard-coded' into a program. For the quick-tip I use the indicator from tutorial 184.

EasyLanguage legacy color reserved words: Black, Blue, Cyan, Green, Magenta, Red, Yellow, White, DarkBlue, DarkCyan, DarkGreen, DarkMagenta, DarkRed, DarkBrown, DarkGray, LightGray,

You might also be interested in QuickTip 33 which demonstrates a method to allow the use of colors from the color class in the Plot statement.

https://markplex.com/free-tutorials/tradestation-easylanguage-quicktips/quick-tip-80-how-to-change-a-color-hard-coded-in-a-program/