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