According to many reports, the "UP color season" is the last week in September and the first 2 weeks in October" That being said, it depends more on temperatures for any given year than on the calendar. I've seen the "peak color" as late as deer season (Nov 15th) and as early as Labor Day weekend. While those are definitely the outside dates, "peak color" times change dramatically from year to year, but expecting to see more than a few "left over trees" the end of October is being far more optimistic that I would encourage....
Here are a couple of websites that might help you decide:
http://www.uptravel.com/fall-color-routes--55/
http://www.michigan.org/fall/
There is a "bucketload" of things to see and do along the southern shore or Lake Superior. The trip can be very rewarding no matter the time of year, but if "fall color" is your main reason for visiting, the "end of October" is probably not a good time to schedule your trip.