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