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