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)(11,14)(12,17)(13,16)(15,20)(18,22)(19,24)(21,23)(25,26,30,31)(27,28,34,33)(29,32,39,40)(35,36,37,38)(3,7)(5,8)(10,11)(15,17)(16,18)(23,24)(25,26,30,31)(27,33,34,28)(29,32,39,40)(35,38,37,36)(1,2)(3,5)(4,6)(7,8)(10,11)(15,17)(16,18)(23,24)(26,31)(27,34)(32,40)(35,37) involution — undirected(1,3)(2,5)(4,7)(6,8)(9,11,14,10)(12,17,20,15)(13,16,22,18)(19,23,21,24)(25,27)(26,28)(29,37)(30,34)(31,33)(32,38)(35,39)(36,40)(1,2)(3,5)(4,6)(7,8)(9,12,14,20)(10,15,11,17)(13,21,22,19)(16,24,18,23)(25,28)(26,27)(29,38)(30,33)(31,34)(32,37)(35,40)(36,39)(9,13,14,22)(10,16,11,18)(12,19,20,21)(15,23,17,24)(25,29,30,39)(26,32,31,40)(27,35,34,37)(28,36,33,38)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.