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