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