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