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