so it depends on which graphs you're talking about.
if you're talking about the horizontal bar graph above the BiB section, the lighter colored sections are your target ranges for each stat. builds that have those stat ranges are in the very top of possible builds.
if you're talking about the one on the gearing strategy report screen that has a bunch of vertical bars that start red on the left and turn green as they go right, that is showing many possible distributions of stats. the more green the bars, the better the results with that distribution. this is a good way to see in general the kind of stat distributions you want by looking at which stats are high on the right and which aren't. if you're using BiB though, the site handles that for you.