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