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