\version "2.19.17"

colorGrob =
#(define-music-function (parser location my-grob my-color color-on)
   (symbol? color? boolean?)
   ;; check for the boolean argument
   (if color-on
       ;; either set the color for the grob type
       #{
         \temporary \override #my-grob #'color = #my-color
       #}
       ;; or revert it
       #{
         \revert #my-grob #'color
         
       #}))

colorGrobs =
#(define-music-function (parser location my-grob-list my-color color-on)
   (symbol-list? color? boolean?)
   (if (null? my-grob-list)
       ;; issue an empty music expression
       #{ #}
       #{
         % color the first grob type of the current list
         \colorGrob #(car my-grob-list) #my-color #color-on
         % recursively call itself with the remainder
         % of the current list.
         \colorGrobs #(cdr my-grob-list) #my-color #color-on
       #}))

colorMusic =
#(let ((grob-names (map car all-grob-descriptions)))
   (define-music-function (parser location my-color music)
     (color? ly:music?)
        #{
          \colorGrobs #grob-names #my-color ##t
          #music
          \stopStaff
          \colorGrobs #grob-names #my-color ##f
          \startStaff
          #}))


colA = #(define-music-function(parser location music)(ly:music?)
          #{
            \colorMusic #(rgb-color 0.72 0 0.196) #music
          #})



music = {\repeat unfold 40 a4}

  
  \new StaffGroup {
    <<
    \set StaffGroup.systemStartDelimiterHierarchy =
        #'(SystemStartBar (SystemStartBrace (SystemStartBracket a b)))
        \new Staff \colA { <<{\voiceTwo a a\music \music}\new Voice  \relative c''\colA {\music }>>}
        \new Staff {\music \music}
  >>
}