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