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