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