Ashley Kahn's A Love Supreme, covering the development of Coltrane up to the recording of ALS devotes about 20 pages to the structure of it. I haven't time now (I'm on my way out), but I'll try and summarize what that has to say later.

Coltrane had been an addict at one time and Miles Davis dropped him from his group because of it. He went off and cleaned up and found God or a certain spirituality. ALS can be considered a hymn and the intensity of the playing is as important as what he plays, either praising a creator or giving thanks for his gifts.

I'll try and get back to this later, but in the meantime I had just did a quick search for help online; there's a wikipedia article with some references that you might follow up. Also this article All About Jazz - John Coltrane, A Love Supreme and GOD (some strange characters in it).

Also for a formal approach to a part of it you could have a look at pp37-40 of this Thesis (haven't time to give it more than a glance just now).

Mick