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