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