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