I found the following summary in the article cited here. It is behind a paywall, and too long to quote, but the list may be useful.
How a Department Diversified: In Brief
About a decade ago, Penn State’s philosophy department decided that it wanted a more diverse graduate-student body. Here’s what it has done toward that goal.
Changed recruitment: Instead of waiting for applications to roll in, faculty members search for talent at the undergraduate level and have developed relationships with historically black colleges.
Revamped the curriculum: The department focused on critical philosophy of race, which has helped to make the curriculum more attractive to those who haven’t traditionally been represented in philosophy.
Hired a diverse group of professors:Five of the 15 faculty members today are women, and three are members of underrepresented minorities, signaling to graduate applicants the department’s commitment to diversity.
Provided extra financial support: Students can apply for additional grants for the summer — a crucial step, some faculty members say, in attracting and retaining underrepresented students, who disproportionately come from lower-income backgrounds than their white counterparts do.
Created an intellectual community:Many faculty members conduct research on critical philosophy of race. In 2013 the department started an academic journal on the topic. Within philosophy, Penn State has become known for this specialty, which also helps with recruitment.