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