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