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