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