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