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