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