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