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