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