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