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)(16,21)(17,20)(18,22)(23,27)(24,28)(25,26) involution — undirected(2,3)(6,9)(10,12)(13,15,17,23)(14,19,20,27)(16,25,18,24)(21,26,22,28)(1,2,4,3)(5,7,8,11)(6,10,9,12)(14,20)(15,23)(21,22)(24,25)(1,3,4,2)(14,20)(15,24)(16,18)(19,26)(23,25)(27,28)(6,9)(10,12)(13,16,17,18)(14,21,20,22)(15,25,23,24)(19,26,27,28)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.