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