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