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