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