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