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