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