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