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