I did a little research on this. Here is a link to the paper in which he described the snake. Publication date was December 2005. There is one color photograph within the document.
http://www.fieldmuseum.org/research_...uliya_2005.pdf
Mention of the color changing observation is basically anecdotal. A short paragraph at the end of the paper mentions the observation occurring in 2003. Perhaps the quote from the article is a verbal one from the author speaking with Auliya, but the paper only says after a period of time, it doesn't specifically say a few minutes later.
The ability to shift coloration is common among many species of snakes, but the ability to effect that change rapidly is rather uncommon. In the vast majority of cases the color change is attributed to the effects of photoperiod and takes 90 minutes or more to complete. An exception to this is Crotalus viridis which has been observed to shift color from dark to light in as little as a few minutes in response to temperature changes or increased activity.
I believe the author of the article, or perhaps the fellow from the World Wildlife Fund, came up with the "chameleon like" analogy. Auliya himself, at least publicly, never alluded to the idea that it was an intentional change of color for the purpose of camouflage, or otherwise the result of a physical effort on the part of the snake.
It appears he considered it an interesting aspect of its physiology, but not important enough to warrant detailed mention in the published description of the species.