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