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