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