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