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