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