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