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