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