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