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