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