PDO is an odd stat in my opinion. The league average is 1.00 and it's supposed to measure a team's luck. As stated above, it uses the team's shooting percentage + their save percentage, so if you're over 1.00, you're getting lucky because typically high shooting and save percentages are unsustainable (example would be Pirri's shooting percentage of 15 percent last year).
So pretty much the graph is saying we're giving up more scoring chances than we're getting, and we're also getting lucky offensively and defensively. Defensively would be mostly because of Luongo and Montoya having a decent save percentage. Our PDO is about average actually, but we look like an outlier because of the fact that we're giving up more scoring chances than we're getting.