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