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