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)(11,18)(12,13)(14,15)(16,19)(17,22)(20,21)(23,24)(25,26,30,33)(27,28,35,31)(29,32,38,40)(34,36,37,39)(1,3,6,8)(2,7,4,5)(10,15)(11,19)(12,22)(21,23)(25,27)(26,31)(28,33)(29,37)(30,35)(32,36)(34,38)(39,40)(2,4)(3,8)(10,15)(12,22)(16,18)(20,24)(29,38)(32,40)(34,37)(36,39) involution — undirected(3,8)(5,7)(9,11,14,19)(10,16,15,18)(12,20,22,24)(13,23,17,21)(25,28,30,31)(26,27,33,35)(29,36,38,39)(32,34,40,37)(1,4,6,2)(3,7,8,5)(9,12)(10,17)(11,20)(13,15)(14,22)(16,21)(18,23)(19,24)(25,29)(26,32)(27,34)(28,36)(30,38)(31,39)(33,40)(35,37)(1,5,6,7)(2,8,4,3)(9,13,14,17)(10,12,15,22)(11,21,19,23)(16,24,18,20)(25,27)(26,28)(29,34)(30,35)(31,33)(32,36)(37,38)(39,40)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.