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