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