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