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