How about something along the lines of a “short straw”, dividing the 40 people into Groups, then having “Rounds” like boxing rounds. Ding Ding!
Round 1
Divide the 40 people into 8 groups of 5 people.Each Group draw straws – short one wins that groups round and is eligible for Round 2.You can have the 8 Groups draw all at once or stagger the Group drawings.You now have 8 people ready for Round 2.Divide them into 4 Groups of 2 people.
Round 2
Like Round 1, each Group draw straws – short one wins that groups round and is eligible for the Final Round.You can have the 4 Groups draw all at once or stagger the Group drawings.Now, you can go to a Round 3 of 2 Groups with 2 people each OR go to the Final Round with 1 Group of 4 people.
Round 3
If you went with the Round 2 winners divided into 2 Groups of 2 people each, short stick in each Group goes to the Final Round.
Final Round
Here we go! Short straw wins it all!