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