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