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