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