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)(25,26,30,32)(27,31,35,38)(28,29,36,37)(33,34,39,40)(1,2)(3,4)(5,6)(7,8)(10,14)(12,21)(15,17)(19,24)(25,27,30,35)(26,31,32,38)(28,33,36,39)(29,34,37,40)(2,6)(3,7)(10,14)(11,18)(16,20)(19,24)(26,32)(28,36)(31,38)(33,39) involution — undirected(9,11)(10,15)(12,19)(13,18)(14,17)(16,22)(20,23)(21,24)(25,28)(26,29)(27,33)(30,36)(31,34)(32,37)(35,39)(38,40) involution — undirected(1,3,5,7)(2,4,6,8)(9,10)(11,15)(12,16)(13,14)(17,18)(19,22)(20,21)(23,24)(25,27)(26,31)(28,33)(29,34)(30,35)(32,38)(36,39)(37,40)(1,4)(2,7)(3,6)(5,8)(9,12,13,21)(10,16,14,20)(11,19,18,24)(15,22,17,23)(25,29)(26,28)(27,34)(30,37)(31,33)(32,36)(35,40)(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.