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