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