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