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)(26,30)(28,36)(31,33)(34,40)(1,2)(3,5)(4,6)(7,8)(9,11,14,21)(10,15,18,19)(12,20,22,13)(16,17,23,24)(25,26)(27,33)(28,32)(29,30)(31,35)(34,39)(36,37)(38,40)(1,2,4,6)(3,7,8,5)(12,22)(13,20)(16,23)(17,24)(25,26,29,30)(27,31,35,33)(28,32,36,37)(34,38,40,39)(3,8)(5,7)(9,10)(11,15)(12,23)(13,17)(14,18)(16,22)(19,21)(20,24)(25,26)(27,31)(28,32)(29,30)(33,35)(34,38)(36,37)(39,40) involution — undirected(1,3,4,8)(2,5,6,7)(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)(32,38)(36,40)(37,39)(1,2)(3,5)(4,6)(7,8)(9,13,14,20)(10,17,18,24)(11,12,21,22)(15,23,19,16)(25,28,29,36)(26,32,30,37)(27,34,35,40)(31,38,33,39)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.