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