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