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