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