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