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