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