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