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