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