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