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