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