Hi there,
I'm sorry to hear you didn't get into Booth! Great question though. First things first, don't ask them about why you didn't get in. They have NO idea. They received THOUSANDS of applications and if you think they will remember the reason(s) you got dinged, well that isn't happening.
However, you can definitely use this opportunity to not only communicate your story again (hopefully a bit stronger this time around) but also learn more about why Booth. Ask them to share their perspectives or the stories of students who were in similar positions as you. Ask them about what Booth is doing to improve the things that need improving.
There is no specific list of questions but keep this overarching concept in mind: don't ask them too many pointed questions (e.g. why didn't I get in?) but rather focus on higher level questions that not only let you learn more, but also (in a subtle way) show off you know you're a great fit. Use the opportunity to establish a relationship that you can leverage strategically later in the process if you have questions or are visiting campus.
They are on a whirlwind tour and they're going to meet thousands of applicants just like you. You can stand out from the pack by not trying to stand out too much. If that doesn't make sense now, it will once you get there

I hope that helps,
Bhavik