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