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