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