There's a lot about the Grateful Dead that could be included under the heading of chaos.
Carol Brightman's book about the band is appropriately titled Sweet Chaos. Reviewer David Hadju is not as kind on either the book or the band as Rolling Stone is. (Read the NYT review here).
As tour manager Sam Cutler from the early 70s notes in the 6 part Amazon series called Long Strange Trip, the band's lack of a leader meant a fair amount of chaos reigned, that decisions were difficult to make. Garcia ends up being a reluctant leader in the public eye, but it is the last thing he really wants.
One of the outstanding decisions the band does make, however, is their concert taping policy: scores of fans would show up to concerts with sophisticated taping equipment - with the band's blessing. In the Amazon material, Garcia comments that once the band has played their show, he is more than happy for that night's material to be of use to other people since he is done with it. It's that policy that makes it easy to share this with you.
Most shows had two sets: a more structured sequence of their classic, recognizable songs and a less structured set that some of the band describe as part of their role as travel enablers: aiming to take the audience on a trip.
From the hundreds of free recordings available at the Internet Archive, you can listen to versions of the same songs done over the years and hear the variations in solos, vocals and improvisation. "Playing in the Band" might be 7 minutes one night and 23 the next. Another song might begin as a kind of wandering cacophony before breaking into its recognizable form. Others just wander in loosely structured chaos, such as this version of "Space"
for more tunes from that particular concert (04/07/85 at Philly's Spectrum) click here.