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