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)(15,19)(16,24)(17,18)(20,22)(21,26)(23,27)(25,28) involution — undirected(2,4)(6,9)(10,12)(13,15,19,14,20,17,18,22)(16,23,26,21,27,24,25,28)(1,2,3,4)(13,16)(14,21)(15,23)(17,24)(18,25)(19,26)(20,27)(22,28)(5,7,8,11)(6,10,9,12)(13,17,18,14,20,15,19,22)(16,24,25,21,27,23,26,28)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.