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