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