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