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