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)(14,20)(15,25)(17,18)(21,26)(22,28)(23,24) involution — undirected(5,7)(6,9)(8,11)(10,12)(13,14,18,20,19,24,17,23)(15,26,25,27,22,21,28,16)(2,4)(7,11)(9,12)(13,15,18,25,19,22,17,28)(14,21,20,16,24,26,23,27)(7,11)(9,12)(13,16)(14,22)(15,24)(17,21)(18,26)(19,27)(20,28)(23,25) involution — undirected(6,10)(9,12)(13,17,19,18)(14,23,24,20)(15,25,22,28)(16,26,27,21)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.