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