A coloring of a graph $G$ with vertex set $V$ is the partitioning of $V$ into so-called color classes so that no two vertices of the same class are adjacent. A $k$-coloring contains exactly $k$ color classes.
We shall think of a $k$-coloring of $G$ as a map $\psi: V \rightarrow\{1,2, \ldots, k\}$ such that $\psi^{-1}(i), i=1,2, \ldots, k$, are the color classes of $G$. Naturally two maps, $\psi_1$ and $\psi_2$, represent the same $k$-coloring if and only if $\psi_1=\psi_2 \circ \pi$ for some permutation $\pi$ of $\{1,2, \ldots, k\}$.
My goal is: given a graph with two $k$-colorings, I want to determine if they are the same. I am unsure which function to use. Ultimately, the final objective is to determine how many different $k$-colorings the graph has in total.
For example,
g1 = Graph[{a \[UndirectedEdge] b, b \[UndirectedEdge] c,
c \[UndirectedEdge] d, d \[UndirectedEdge] a,
a \[UndirectedEdge] c}, VertexLabels -> "Name"]
vertexColorings = ResourceFunction["FindProperColorings"][g1, 3]
We obtained six $3$-colorings, and are they the same? How to represent permutations of vertices in the definition using a function in Mathematica?
{{1, 2, 3, 2}, {1, 3, 2, 3}, {2, 1, 3, 1}, {2, 3, 1, 3}, {3, 1, 2, 1}, {3, 2, 1, 2}}
After that, we may obtain all uniquely colorable simple graphs up to 10 vertices. See https://oeis.org/A369223 corresponding to their counts.
Additional information: The chromatic number of $G$, denoted by $\chi(G)$, is the minimal $k$ for which $G$ has a $k$-coloring. A graph with exactly one $k$-coloring is called uniquely $k$-colorable. It is obvious that if $G$ is uniquely $k$-colorable then $\chi(G)=k$ or $n$, so we shall say simply that $G$ is uniquely colorable if it is uniquely $\chi(G)$ colorable.