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