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