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