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