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