Plenty of different ways people have dealt with dangling straps. I really like using Velcro cable ties like below. Not only are they great for holding straps, they can come in handy when in the field for numerous other uses.
I thought about this, and even made some Velcro strips of my own. But when it got cold, windy or I was in a hurry...which one or all of these seems to be the norm...I found myself just shoving the excess straps into the folds and voids of the bag and they stay put just fine.