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