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