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