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