reserve color for a meaningful purpose in graphs
In the "People Reached" graph it you are using color do designate the number of people reached. This information is also represented by the Y coordinate. You should reserve color for another purpose. Just trying to think like Tufte here.
AdminDavid (Co-Founder, Crowdbooster) commented
Peter, the double encoding of information is a good point, and we're striving to improve the data density so you can really see all the relevant info in one glance (data-ink ratio in Tufte's terms).
We're trying to think of the best way to present this without encoding too much info across the dimensions (X, Y, color, size), so we'll work towards a good balance.