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