permutation matrix to permutation groups element

edit

You just have to find the position of 1 in each column:

sage: M = matrix([[1, 0, 0],[0, 0, 1],[0, 1, 0]])
sage: sigma = Permutation([list(v).index(1)+1 for v in M.columns()])
sage: sigma
[1, 3, 2]
sage: sigma.to_matrix() == M
True