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