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