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