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