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