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