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