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