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