You see 40-star recruits on the X-axis, and 5-star recruits on the Y-axis. The color is determined by the number of 3-star recruits, dark red (less) to dark green (more). Finally, the size of each circle is the average final AP ranking of the teams in the conference. Unranked teams have a ranking of zero, so they are filtered out.
It's not surprise that the SEC dominates the recruiting world, but this chart, which show the total numbers of highly prized recruits, illustrates that very clearly. The SEC's positions in the upper right corner indicates that as a conference, the teams in the SEC which finished ranked in the AP Top-25 signed nearly twice as many 4-star recruits as any other conference and 30% more 5-star recruits. The dark green color of the SEC circle also shows that they landed the most 3-star recruits. Finally, the size of the SEC circle indicates the number of teams which finished ranked in the AP Top 25 was better than any other conference.
The data for this analysis is available for download from my public dropbox account.