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