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