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