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