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