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