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