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