One vertex per element, one color per generator, with an edge from x to x·s.
(2,4)(5,6)(7,10)(8,11)(9,12)(13,14)(15,20)(16,26)(17,24)(18,22)(19,23)(21,27)(25,28) involution — undirected(1,2,3,4)(5,7)(6,9)(8,12)(10,11)(13,15,19,16)(14,20,23,26)(17,27,18,25)(21,22,28,24)(7,12)(9,10)(13,16,19,15)(14,21,23,28)(17,27,18,25)(20,22,26,24)(5,7)(6,10)(8,12)(9,11)(13,17,19,18)(14,22,23,24)(15,25,16,27)(20,21,26,28)(7,12)(9,10)(14,23)(20,26)(21,28)(22,24) 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.