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