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