One vertex per element, one color per generator, with an edge from x to x·s.
(9,10)(11,17)(12,15)(13,16)(14,19)(18,23)(20,22)(21,24)(25,26,31,28)(27,34,37,40)(29,33,30,38)(32,39,35,36)(1,2)(3,7)(4,6)(5,8)(9,11)(10,14)(12,18)(13,19)(15,21)(16,17)(20,24)(22,23) involution — undirected(1,3)(2,5)(4,8)(6,7)(9,12,13,20)(10,15,16,22)(11,18,19,24)(14,21,17,23)(25,27)(26,32)(28,35)(29,36)(30,39)(31,37)(33,40)(34,38)(2,6)(3,8)(11,19)(14,17)(18,24)(21,23)(25,28,31,26)(27,35,37,32)(29,33,30,38)(34,36,40,39)(2,6)(5,7)(10,16)(14,17)(15,22)(21,23)(25,29,31,30)(26,33,28,38)(27,36,37,39)(32,40,35,34)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.