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