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