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