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