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