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