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