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