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