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