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