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