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