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