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