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)(11,16)(12,22)(13,15)(14,18)(17,23)(19,24)(20,21)(25,26)(27,35)(28,29)(30,32)(31,34)(33,40)(36,37)(38,39)(1,3,5,8)(2,6,4,7)(9,11)(10,16)(12,14)(13,20)(15,21)(17,24)(18,22)(19,23)(9,12,15,23)(10,17,13,22)(11,19,21,14)(16,18,20,24)(25,27,31,30)(26,32,34,35)(28,38,33,36)(29,37,40,39)(9,12)(10,17)(11,14)(13,22)(15,23)(16,24)(18,20)(19,21)(25,28,31,33)(26,29,34,40)(27,36,30,38)(32,39,35,37)(1,2,5,4)(3,6,8,7)(9,13,15,10)(11,20,21,16)(12,22,23,17)(14,18,19,24)(25,29)(26,33)(27,37)(28,34)(30,39)(31,40)(32,36)(35,38)(1,4,5,2)(3,7,8,6)(9,14)(10,18)(11,12)(13,24)(15,19)(16,22)(17,20)(21,23)(25,30,31,27)(26,32,34,35)(28,38,33,36)(29,39,40,37)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.