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