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