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