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