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)(16,24)(18,21)(19,23)(20,25)(22,28)(26,27) involution — undirected(1,2)(3,4)(5,7,9,8)(6,10,11,12)(13,15)(14,20)(16,22)(17,21)(18,25)(19,26)(23,28)(24,27)(5,8,9,7)(6,10,11,12)(13,16)(14,21)(15,25)(17,28)(18,19)(20,27)(2,4)(13,17)(14,22)(15,24)(16,27)(18,20)(19,28)(21,26)(23,25) involution — undirected(6,11)(10,12)(13,16,18,19)(14,23,21,24)(15,22,25,26)(17,27,20,28)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.