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