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