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