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