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