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