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