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