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)(21,22,24,23)(25,26,30,33)(27,31,35,29)(28,36,39,32)(34,38,37,40)(1,2)(3,5)(4,6)(7,8)(10,15)(11,20)(12,18)(22,23)(25,27)(26,31)(28,37)(29,33)(30,35)(32,38)(34,39)(36,40) involution — undirected(2,3)(6,7)(10,15)(12,18)(16,19)(21,24)(25,28,30,39)(26,32,33,36)(27,34,35,37)(29,38,31,40)(4,8)(6,7)(9,11)(10,16)(12,21)(13,23)(14,20)(15,19)(17,22)(18,24)(25,29)(26,27)(28,38)(30,31)(32,34)(33,35)(36,37)(39,40) involution — undirected(1,3,5,2)(4,7,8,6)(9,12,14,18)(10,17,15,13)(11,21,20,24)(16,22,19,23)(25,28)(26,32)(27,34)(29,38)(30,39)(31,40)(33,36)(35,37)(1,4)(2,6)(3,7)(5,8)(9,13,14,17)(10,18,15,12)(11,22,20,23)(16,21,19,24)(25,27)(26,31)(28,34)(29,33)(30,35)(32,40)(36,38)(37,39)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.