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