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