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