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