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