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