The blue seems to signify aquatics (diving, rowing, sailing, etc.) except that at the bottom of the chart (clipped), weightlifting has the same blue. The four types of cycling come in three colors. A legend would be a very useful thing here. Like F&J, I kept staring at the chart hoping for inspiration but nothing is forthcoming.
Would prefer also to see the sports shown in order of earliest start date, as opposed to alphabetical.
I find other aspects of this chart attractive. There is an impressive amount of details, like which days the event finals are held. Mousing over the medal symbols produces some useful data:
The daily view provides even more details:
The details are nicely wrapped in layers.
Taking a step back, it would be interesting to understand who the designer has in mind when he/she created this chart. I could imagine a journalist trying to get a quick overview of the day's events but then the chart doesn't provide the venues. An avid fan might want to figure out what's on TV but then consulting a true TV schedule would be better since no station is unlikely to show everything, and they can't show simultaneous competitions anyway.