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