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