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