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