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