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