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