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