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