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