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