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