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