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