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