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