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)(13,14,18,21,17,22,16,26)(15,23,24,28,25,19,27,20)(5,7)(6,9)(8,12)(10,11)(13,15)(14,19)(16,27)(17,25)(18,24)(20,21)(22,23)(26,28) involution — undirected(1,2,3,4)(13,15)(14,20)(16,24)(17,25)(18,27)(19,21)(22,28)(23,26)(7,12)(9,11) involution — undirected(6,10)(9,11)(13,16,17,18)(14,21,22,26)(15,24,25,27)(19,28,23,20)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.