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