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