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