The interviewer truly wants to understand the role that you naturally take on, when put into a team based environment. If you tend to take the lead, let the interviewer know this, but avoid sounding overbearing. If you usually like to generate new ideas and allow someone else to execute them, share your creative side but express that you prefer for others to take the lead.
"I am usually the 'ideas person' in team projects. In my current position, I am not the strongest sales person, but I am highly creative. This means that, in most projects, I am great at creating a plan of action but am most comfortable passing the final client-facing tasks to our more extroverted personnel."
"I definitely like to take the lead on team projects. I am very vocal and organized which makes me a natural leader."
"When it comes to team projects I do not mind taking a backseat and, rather than being the leader, being more of an administrator. I like to organize data and analyze progress rather than lead others."