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