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