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)(11,15)(17,18,20,22)(19,21,24,23)(25,26,30,28)(27,33,34,31)(29,36,37,32)(35,38,40,39)(1,3,5,4)(2,6,7,8)(9,10,13,12)(11,14,15,16)(17,18)(19,21)(20,22)(23,24)(27,34)(29,37)(31,33)(32,36)(3,4)(6,8)(11,15)(14,16)(17,18,20,22)(19,21,24,23)(25,27,30,34)(26,31,28,33)(29,35,37,40)(32,38,36,39)(1,4,5,3)(2,6,7,8)(9,11,13,15)(10,14,12,16)(17,18)(19,23)(20,22)(21,24)(25,28,30,26)(27,31,34,33)(29,36,37,32)(35,38,40,39)(1,2)(3,6)(4,8)(5,7)(9,12,13,10)(11,14,15,16)(17,19)(18,21)(20,24)(22,23)(25,29)(26,32)(27,35)(28,36)(30,37)(31,38)(33,39)(34,40)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.