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