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