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