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