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