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