The arrow colors represent the rhythm in comparison to the song. If you understand music theories/rhythms, this should make a lot of sense to you.
Red = 4th note (or quarter note)
Blue = 8th note (or eighth note)
Purple = 12th note (or eighth note triplet, in musical notation)
Yellow = 16th note (or sixteenth note)
Pink = 24th note (or sixteenth note triplet, in musical notation)
Orange = 32nd note (or thirty-second note)
Teal = 48th note (or thirty-second note triplet, in musical notation)
Green = 64th note (or sixty-fourth note)
White = 96th/192nd (any notes not represented above will be white)
Red = 4th note (or quarter note)
Blue = 8th note (or eighth note)
Purple = 12th note (or eighth note triplet, in musical notation)
Yellow = 16th note (or sixteenth note)
Pink = 24th note (or sixteenth note triplet, in musical notation)
Orange = 32nd note (or thirty-second note)
Teal = 48th note (or thirty-second note triplet, in musical notation)
Green = 64th note (or sixty-fourth note)
White = 96th/192nd (any notes not represented above will be white)