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