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