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