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