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