It's almost too obvious to say that All the Colors of the Dark (with the crazy AKAs Day of the Maniac and They're Coming to Get You!) has a dream-like quality seeing as we start on the fetching Edwige Fenech's literal nightmare. Her character Jane has been having these vivid dreams and perhaps some hallucinations as well ("perhaps" allowing for some gaslighting here) since she lost her baby in a car accident. As a disturbing psychological piece, the film effectively combines resentment for the driver (her fiancé), for herself as a bad mother, for her own mother, too. As a horror film, it's got the requisite sex and violence - indeed, even when the ladies are dressed, it's often as if they were naked - and a satanic cult, and maybe even supernatural powers. As a giallo (that is to say, based on murder mystery fiction), it requires a solution at the end that's, in this case, a bit heavy on the exposition, and we wake up from the nightmare. Or almost. It's easy to get a little lost in this one. Just accept it as a mood piece.

A film I enjoyed but was baffled by for several reasons. Listening to the audio commentary didn't help either with it being mostly an overview of giallo cinema and the aesthetics of the film, and very little analysis of the plot. Reading articles just confuse me with interpretations wildly different from mine. Does anyone know of a good analysis of this?

From Mikel Koven's book La Dolce Morte: Vernacular Cinema and the Italian Giallo Cinema:
But it is the actions of Jane’s partner, Richard, that begin to complicate the presumed polarity between “good, normal people” and “evil, wicked Satanists”: in protecting Jane and himself from the coven’s clutches, he murders just as many people as Mark. Richard kills Mark with a pitchfork, shoots Jane’s sister Barbara (Susan Scott) dead for also being a member of the coven, and ends up pushing the coven leader off the roof. If Richard kills just as many people as the coven does, what is the difference between the two? It is true that Richard does not torture puppies, but he is having an affair with Barbara while her sister is recovering from losing their baby, and then he ends that relationship by shooting her. The film vilifies witchcraft as an evil practice, but the actions of the supposedly heroic characters undercut that moral certainty.

What is he talking about? Richard kills three people in self-defence but the author is passing it off like he's just as bad as McBrian. Also, what affair? Richard visits Barbara twice - first to talk about Jane then to accuse her of being in the cult. Barbara is first trying to seduce then kill Richard. Nothing in their dialogue suggests an affair.

Almost goes without saying, but the use of color in this is phenomenal! So lush and beautifully shot, mixed with some delirious story telling and psychedelic editing and you get some top-tier giallo.

Unfortunately the ending is pretty lackluster.