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