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