One vertex per element, one color per generator, with an edge from x to x·s.
(2,3)(5,6)(7,11)(8,12)(9,10)(14,18)(19,25)(20,21)(26,27) involution — undirected(2,3)(6,10)(11,12)(13,14,16,18)(15,19,22,25)(17,20,24,21)(23,27,28,26)(1,2,4,3)(5,7,9,8)(6,11,10,12)(13,15,16,22)(14,19,18,25)(17,23,24,28)(20,27,21,26)(1,3,4,2)(5,8,9,7)(6,12,10,11)(14,20)(15,22)(17,24)(18,21)(19,26)(25,27)(6,10)(11,12)(15,22)(19,25)(23,28)(26,27) involution — undirectedA Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.