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