One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,4)(5,6)(7,9)(8,10)(11,12)(13,14)(15,23)(16,20)(17,21)(18,22)(19,25)(24,28)(26,27) involution — undirected(2,4)(13,15)(14,19)(16,24)(17,25)(18,26)(20,23)(21,27)(22,28) involution — undirected(6,9)(7,12)(10,11)(13,14)(15,23)(16,20)(17,21)(18,22)(19,25)(24,28)(26,27) involution — undirected(6,10)(9,11)(13,16,18,17)(14,20,22,21)(15,24,26,25)(19,23,28,27)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.