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