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