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