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