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