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)(15,16)(17,18)(19,20)(21,22)(23,26)(24,28)(25,27) involution — undirected(6,8)(10,11)(14,18)(16,19)(21,23,25,24)(22,26,27,28)(5,7)(6,10)(8,11)(9,12)(13,14,17,18)(15,19,20,16)(21,24,25,23)(22,26,27,28)(1,2)(3,4)(5,7)(6,10)(8,11)(9,12)(13,15)(14,19)(16,18)(17,20)(21,22)(23,26)(24,28)(25,27) involution — undirected(5,8,9,6)(7,11,12,10)(13,16,17,19)(14,15,18,20)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.