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