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