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)(15,18)(16,24)(17,21)(19,22)(20,27)(23,28)(25,26) involution — undirected(1,2)(3,4)(6,10)(11,12)(13,15)(14,18)(16,24)(17,22)(19,21)(20,26)(23,28)(25,27) involution — undirected(2,4)(5,7,9,8)(6,11,10,12)(13,16,18,27,19,28,17,26)(14,20,21,24,22,25,15,23)(1,2)(3,4)(5,8,9,7)(6,12,10,11)(13,14)(15,17)(16,25)(18,21)(19,22)(20,28)(23,27)(24,26)(2,4)(13,17,19,18)(14,21,22,15)(16,26,28,27)(20,24,25,23)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.