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