Below is the only known reference to the Laws of Color and of Music and Rhythm by Alice A. Bailey (AAB) in her voluminous writings and those given to her by Djwhal Khul (DK). Links on these pages of the Laws of Alice A. Bailey are to the online books at the Lucis Trust website.
For a discussion of what AAB means by a “law” please see Alice A. Bailey – What is a Law?
Not much information here other than there are these 27 occult laws which are not now published and you will learn after some stage of initiation? Possibly of interest is the mention of the “fourth Ray of Harmony,” although in most of AAB’s work this is expressed as the “fourth Ray of Harmony through Conflict.” I did see this here:
2. The personality ray—the fourth Ray of Harmony.
3. The ray of the mind—the fourth Ray of Harmony.
Some definitions of “occult” that might be of interest:
The laws of fire will be gradually permitted exoteric publication; there are twenty-seven occult laws which are only revealed after initiation at this stage of evolution. In them are summed up the basic laws of color and of music and rhythm. When music produces warmth or stimulation, and when pictures, for instance, glow or reveal the subjective within the objective, then will this fourth Ray of Harmony be coming to fruition.
You are welcome to post your comments and understanding of this law.