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