Hi,

I would recommend the following structure:

1. Start with a 1 sentence summary of your background, why you are relevant for McKinsey and what's your unique selling point
2. Talk about 3-4 of your roles (may be professional, education, extracurricular), 3 sentences each. The more experienced you are the more you should speak about professional roles. It can be also the distinct roles within the same organization. Typical structure: 1) What was the company 2) What you were responsible for 3) Greatest achievement in that role, that will stay in the memory of the interviewer (E.g. While working at Adidas supply chain I was personally responsible for the delivery of soccer balls to the Worldcup in Africa)
3. The main reason why consulting (or McKinsey if you were a consultant before) is the next logical career step for you

Best!