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