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