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