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