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