I think that a leader in the CHAOSS community is someone who helps advance the project by contributing directly and coordinating work with others. Leaders should regularly attend the weekly community meetings to report on the work of their respective working group.
Leadership sets the tone for the culture, values, and communication style for everyone else. I think a CHAOSS leader (whether it be informal or formal) should embody and foster empathy, compassion, and respect for everyone else working on the project, no matter in what capacity. I think that being an excellent communicator and having a passion for helping open source projects prioritize and measure their community's health is also helpful.