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