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