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