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