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