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