### Automorphism group of ~~coxeter ~~Coxeter groups

Coxeter groups can be invoked using the comment

`W = `~~CoxeterGroup(['A',3],implementation='reflection'). ~~CoxeterGroup(['A',3],implementation='reflection')

Now, W has three simple reflections S_1, S_2 and S_3. and I am interested in studying the automorphism S_1 -----> S_3, S_2 -----> S_2 and S_3 -----> S_1. Can any one please tell me, how to implement this automorphism of W in sage?

Thank you.