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