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