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