Q: Coloring notes in Lilypond by pitch lilypond can color notes in a arbitrary way using
\override NoteHead #'color = #red c

with the default color is black. But I like to color all notes by pitch, so that my kids can more easily learn to recognize the notes as the c, d, e, f, ... are associated with its own color. The above allows me to do this, but is rather verbose.
Is there a shortcut, macros of some sort, that allow me to do something along the lines of:
redc greend bluee

or even overwriting the default colors for each note by pitch so that I can even simply do:
c d e

and have each of them have a different color?

A: There's a question It is possible to color note heads depending on their pitch? at the LilyPond Snippet Repository. You get the answer by clicking on the stave. 

A: There is an example for this in the snippets:
%Association list of pitches to colors.
#(define color-mapping
  (list
    (cons (ly:make-pitch 0 0 0) (x11-color 'red))
    (cons (ly:make-pitch 0 0 1/2) (x11-color 'green))
    (cons (ly:make-pitch 0 1 -1/2) (x11-color 'green))
    (cons (ly:make-pitch 0 2 0) (x11-color 'red))
    (cons (ly:make-pitch 0 2 1/2) (x11-color 'green))
    (cons (ly:make-pitch 0 3 -1/2) (x11-color 'red))
    (cons (ly:make-pitch 0 3 0) (x11-color 'green))
    (cons (ly:make-pitch 0 4 1/2) (x11-color 'red))
    (cons (ly:make-pitch 0 5 0) (x11-color 'green))
    (cons (ly:make-pitch 0 5 -1/2) (x11-color 'red))
    (cons (ly:make-pitch 0 6 1/2) (x11-color 'red))
    (cons (ly:make-pitch 0 1 0) (x11-color 'blue))
    (cons (ly:make-pitch 0 3 1/2) (x11-color 'blue))
    (cons (ly:make-pitch 0 4 -1/2) (x11-color 'blue))
    (cons (ly:make-pitch 0 5 1/2) (x11-color 'blue))
    (cons (ly:make-pitch 0 6 -1/2) (x11-color 'blue))
    ))

%Compare pitch and alteration (not octave).
#(define (pitch-equals? p1 p2)
  (and
    (= (ly:pitch-alteration p1) (ly:pitch-alteration p2))
    (= (ly:pitch-notename p1) (ly:pitch-notename p2))))

#(define (pitch-to-color pitch)
  (let ((color (assoc pitch color-mapping pitch-equals?)))
    (if color
      (cdr color))))

#(define (color-notehead grob)
  (pitch-to-color
    (ly:event-property (ly:grob-property grob 'cause) 'pitch)))

\score {
  \new Staff \relative c' {
    \override NoteHead #'color = #color-notehead
    c8 b d dis ees f g aes
  }
}



A: OK, for the book Kid's Keyboard Course - Book #1 I bought earlier this year in Cambridge, I now have this color coding:
#(define color-mapping
  (list
    (cons (ly:make-pitch 0 0 0) (x11-color 'magenta))
    (cons (ly:make-pitch 0 1 -1/2) (x11-color 'grey))
    (cons (ly:make-pitch 0 1 0) (x11-color 'grey))
    (cons (ly:make-pitch 0 1 1/2) (x11-color 'grey))
    (cons (ly:make-pitch 0 2 0) (x11-color 'red))
    (cons (ly:make-pitch 0 2 1/2) (x11-color 'red))
    (cons (ly:make-pitch 0 3 -1/2) (x11-color 'green))
    (cons (ly:make-pitch 0 3 0) (x11-color 'green))
    (cons (ly:make-pitch 0 4 -1/2) (x11-color 'blue))
    (cons (ly:make-pitch 0 4 0) (x11-color 'blue))
    (cons (ly:make-pitch 0 4 1/2) (x11-color 'blue))
    (cons (ly:make-pitch 0 5 0) (x11-color 'yellow))
    (cons (ly:make-pitch 0 5 -1/2) (x11-color 'yellow))
    (cons (ly:make-pitch 0 5 1/2) (x11-color 'yellow))
    (cons (ly:make-pitch 0 6 1/2) (x11-color 'purple))
    (cons (ly:make-pitch 0 6 0) (x11-color 'purple))
    (cons (ly:make-pitch 0 6 -1/2) (x11-color 'purple))))

