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