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