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