The wings would be on the Phoenix, a mystical bird, that burns and then rises anew from the ashes. This is symbolic of what is going on at the end of the story when the city is burned out in the bombing, and Montag, Granger and the other book people hope that from the ashes of the burned out city, like the Phoenix, a winged bird, a new society will rise and renew society, improve society.
The winged bird, the Phoenix is a symbol of hope in this book, it is also somewhat religious, as Bradbury uses religious references, such as the Bible and its importance, as well as the Gospels of Matthew, Mark, Luke and John. And, of course Montag's book, Ecclesiastes.
"By ending the book in a fire storm of bombs, there is the sense that this old society of conformity will die and a new one will be born out of the ashes, like the mythical phoenix to which Granger refers."