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