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