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