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