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