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