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