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