It seems likely (and may be known) that it does depend on the permutation representation. However, it is a subtle question as the <em>stable</em> isomorphism class (of any faithful permutation, or in fact arbitrary, representation) does not. Here two extensions $K$ and $K'$ of a field $k$ are <em>stably isomorphic</em> if for some $m$ and $n$ $K(x_1,\ldots,x_m)$ and $K'(x'_1,\ldots,x'_n)$ are isomorphic as $k$-extensions.