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