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)(11,15)(12,16)(13,17)(14,18)(19,22)(20,23)(21,24)(25,26,31,35)(27,32,38,39)(28,30,37,33)(29,34,36,40)(2,5)(6,7)(9,10,14,18)(11,15,16,12)(13,17,21,24)(19,22,23,20)(25,27,31,38)(26,32,35,39)(28,29,37,36)(30,34,33,40)(1,2)(3,6)(4,5)(7,8)(11,16)(12,15)(13,21)(17,24)(25,28,31,37)(26,33,35,30)(27,36,38,29)(32,34,39,40)(1,3)(2,6)(4,8)(5,7)(9,11)(10,15)(12,18)(13,19)(14,16)(17,22)(20,24)(21,23)(25,28)(26,33)(27,29)(30,35)(31,37)(32,40)(34,39)(36,38) involution — undirected(9,12,14,15)(10,16,18,11)(13,20,21,22)(17,23,24,19)(25,29)(26,34)(27,37)(28,38)(30,39)(31,36)(32,33)(35,40)(9,13)(10,17)(11,19)(12,20)(14,21)(15,22)(16,23)(18,24)(25,30,31,33)(26,28,35,37)(27,34,38,40)(29,39,36,32)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.