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