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