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