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