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