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