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