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