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