For an event that includes people other than a small group of friends these are some suggestions that can help your event be a success.
Print out the game materials well ahead of time. Make sure the colors that print out look accurate because in many games the colors are important and if the players can't tell what a specific color is they may have unnecessary challenges.
Be familiar with the puzzles. You should either attempt to solve them yourself ahead of time or at least read through the hints so that you can see how the puzzles are solved. This is helpful if a team has a question that might not be answered directly in the hints section.
Don't make the groups too large or small. In general, you will want groups between 6-12. 8-10 is the ideal group size. This allows all to participate without it being too crowded.
A few suggestions as to what you can do when you have a large group of 40-50+. You can divide your teams into the sizes you feel would work best. Then you can have your teams race to see who can finish the quickest overall, who can finish with using the least number of clues.
Don't be afraid to use the hints! That is what they are there for. If you see a team struggling, don't hesitate to give a hint or two to get them on the right track. You want the teams to have fun and not be overly frustrated.
If you want to make the game a bit easier for your group, you can arrange the clues so that the matching clues are already together. That way they don't need to figure out which clues go together, only the actual puzzle.
Sometimes having multiple game themes available can be a fun thing for your group. That lets the participants select which theme to play which can get them more engaged in the activity.