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