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