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