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