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