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