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