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