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