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