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