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