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