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